Synthesis of Enantiomers of Chiral Ester Derivatives Containing an Amide Group and Their Chiral Recognition by ~1HNMR Spectroscopy

摘要

Enantiomers of chiral ester derivatives containing an amide group, and possessing one or two stereogenic centers were prepared from L- and D-α-amino acids, and glycine with (S)-and (R)-mandelic acid for probing their chiral recognition as a new class of chiral guests by ~1HNMR spectroscopy, since chiral ester derivatives have been rarely used as chiral substrates for chiral recognition by ~1HNMR technology. The results indicated that these chiral ester derivatives have been successfully differentiated in the presence of tetraaza macrocyclic chiral solvating agents (TAMCSAs) 1 a-1 c. In order to better under- stand their chiral discriminating behavior, Job plots, association constants (Ka), and theoretical calculations of (S,S)-G1 and (R,R)-G1, as a representative example, were performed, respectively. In order to evaluate their practical application, the 1HNMR spectra of G1 and G9 with various optical purities were measured (up to 98% ee). In this work, a practical strategy has been effectively established for chiral recognition of chiral ester derivatives containing an amide group and possessing one or two chiral centers in the presence of tetraaza macrocyclic chiral solvating agents 1 a-1 c by means of 1HNMR spectroscopy.